Patent No. 4807031 Interactive video method and apparatus
Patent No. 4807031 Interactive video method and apparatus (Broughton, et al., Feb 21, 1989)
ASSIGNEE: Interactive Systems, Incorporated, Beaverton, OR
Abstract
Method and apparatus for in-band, video broadcasting of commands to interactive devices are described. Control data are encoded by subliminally modulating, prior to the remote, composite video broadcast of video program material, a selected sequence of video image fields. The resulting modulated video fields within the viewing area of a television, each having alternately, proportionately raised and lowered luminance horizontal scan lines, are monitored by a light sensitive device positioned adjacent the user's television screen. A semirigid, twisted pair cable connects the device to nearby receiver/transmitter electronics that discriminate the binary data from the program material and amplitude modulate a high frequency infrared (IR) carrier with the data. Interactive devices, e.g. educational aids or action toys, within range of the wireless IR transmission detect energy in this frequency range, decode the commands embedded in the control data, and selectively execute predetermined actions in response to the data-encoded broadcast. In a proposed modification, low radio frequency (RF) electromagnetic radiation emanating from the television's raster scan electronics is coupled by a conventional RF antenna to the receiver electronics, which identically discriminate the binary data, from the program material, for transmission to the interactive devices.
Notes:
SUMMARY
OF THE INVENTION
Method and apparatus are described that permit the remote control of interactive
devices proximate to a conventional television receiver by the broadcast of
composite video information thereto. The method consists of producing a composite
video signal containing program material and control data by subliminal luminance
and/or chrominance modulation; broadcasting the signal to a television; receiving
the signal by the television; detecting the modulation, at the television, to
reproduce the control data; and locally transmitting the control data to enable
entertainment, educational or other devices within range of the transmission
to respond to the program material in a predetermined manner. The remote control
apparatus includes means for generating a signal containing control data; means
for generating a signal containing a video program; means for modulating the
video program signal by the control data signal in timed relation thereto, thereby
producing a control data-modulated video subcarrier detectable as modulation
in at least one predefined viewing area of the television; means at the television
for detecting such modulation in the viewing area to produce a control data
sequence; and means for controlling, in predetermined response to the control
data sequence, the actions of at least one entertainment, educational or other
device.
The data encoding method of the invention involves modulating a video signal
at frequencies that are related to multiples and submultiples of the horizontal
line rate, to produce a subtle video subcarrier. Although the modulation is
within the viewing area of the television screen, it remains substantially invisible
to the viewer because of its relatively low intensity, its timed relation to
the horizontal line rate and the inherent integration and resolution characteristics
of the human eye. In order to ensure the integrity of the data communication,
while limiting the cost to users of the decoding apparatus, the signal-to-noise
ratio of the communication is increased, in the preferred embodiment of the
invention, by the data encoder's removal of subcarrier components interpretable
as data when a binary 0 is to be encoded, and by the addition of a subcarrier
when a binary 1 is to be encoded (or vice versa). Those skilled in the art will
appreciate that one or more such subcarriers may be data modulated to convey
information, in serial or parallel, in a variety of ways, including, but not
limited to, pulse modulation (PM), phase modulation (PM), amplitude modulation
(AM), frequency modulation (FM), time or pulse interval modulation (PIM), frequency
shift keying (FSK), return-to-zero (RZ), non-return-to-zero (NRZ), or any other
of a variety of spatio-temporal modulation and coding techniques.
In its preferred embodiment, the interactive video apparatus takes the form
of an optical transducer, or light sensitive diode, that may be `aimed` at the
television screen and that is connected via a twisted pair cable to a compact,
battery-powered receiver/transmitter device located nearby. Receiver electronics
reconstruct the control data by detecting the video subcarrier in the modulated
video image and producing a bit-serial signal representing the control data.
Transmitter electronics amplitude modulate an infrared (IR) carrier by the reconstructed
control data and drive an infrared light emitting diode (IRED) array. One or
more interactive toys, which may be separately purchased, detect the carrier,
decode the command field within the control data, and initiate one or more actions
in response thereto.
In a proposed modification to the preferred embodiment, an antenna capable of
intercepting radio frequency (RF) electromagnetic radiation and coupling it
to conventional receiver electronics replaces the optical transducer and twisted
pair cable of the preferred embodiment. It has been found that an inaudible,
but detectable, low RF artifact of the data modulated video subcarrier is produced
by the raster scan electronics of a television which is displaying the composite
video signal described herein. While being of somewhat more limited range, i.e.
the antenna must be located within a few feet of, and in front of, the television
screen, due to the relatively low energy level of the RF emanations, this alternative
embodiment also yields certain advantages the antenna may be located closer
to the screen of the television, as it needs no field of view; and the antenna
is less susceptible to interference from spurious, visible light sources, e.g.
the high frequency emanations of a fluorescent lamp.
Thus, the various objects of the invention are achieved. Subliminal luminance
modulation within a viewing area of the television enables data encoded therein
to be detected, while the modulation remains invisible to a television viewer.
The optical transducer, which may be `aimed` unobtrusively at the television
screen from a range of distances and through a range of angles, semirigidly
extends from the receiver/transmitter device, which may be affixed discretely
to the side of the television receiver, thereby obviating conventionally required
interconnections. The detector, or decoder is simplified and the data communication
rendered more reliable by the data encoder's removal, prior to broadcast, of
video features that otherwise would be interpretable as data. Infrared transmission
between the receiver/transmitter device and interactive devices located in the
room is wireless and inaudible, and imposes no burden on users or non-users
of the interactive video apparatus. The encoding of selective successive fields
of the video image with a serial bit stream of binary data achieves a data rate
adequate to permit real time control, within or outside the context of the video
program material, of multiple interactive devices. Parity error detection logic
within the interactive devices controlled thereby ensures data integrity so
that the interactive devices reliably respond in a predefined manner. The electronics
of the apparatus use conventional logic circuitry and fabrication methods, including
very large scale integration (VLSI), thereby further enhancing the reliability
of the system and reducing its cost.
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The advantages offered by the invention should be apparent to those skilled
in the art. The method and apparatus disclosed herein enable subliminal, in-band,
data communication over conventional television broadcast channels, for ancillary
use at a site local to the home television viewer. Detection apparatus, including
an optical transducer which unobtrusively monitors any desired region within
a program viewing area of the television screen, enables receiver/transmitter
electronics to discriminate control data from random video noise, and locally
to transmit the control data to one or more interactive devices within its IR
transmission range. Such interactive devices flexibly may be programmed to initiate
predefined actions in response to the television program's story line. The apparatus
requires no electrical connections to the television receiver or antenna, and
wirelessly, remotely controls interactive devices within a television viewer's
home. Interactive devices that remotely may be controlled by the method and
apparatus of the invention include educational, as well as entertainment, devices.
It will be appreciated by those skilled in the art that, within the spirit of
the present invention, means for detecting the subliminal modulation of the
video program signal may be embodied in a hand manipulable probe, which probe
itself may be the interactive device remotely controlled by the control data,
thereby obviating the requirement of local communication of the reconstructed
control data. It also will be appreciated that, within the spirit of the invention,
the communication of control data to an interactive device may be accomplished
by other than IR means, e.g. an RF transmitter located adjacent the television
may communicate the control data to an RF receiver within the interactive device,
or an RF antenna- and receiver-equipped interactive device directly may detect
the RF emanations from the television, in accordance with the modification to
the preferred embodiment that is proposed herein.
Accordingly, while a preferred method for practicing the invention, and a preferred
embodiment of the apparatus of the invention and a proposed modification thereto
have been described herein, it is appreciated that further modifications are
possible that come within the scope of the invention.
Comments